From 1fb7bd7fd889941c818cba6b1eb277e90e61dc9c Mon Sep 17 00:00:00 2001
From: Daniel Kozak <kozzi11@gmail.com>
Date: Wed, 26 Jul 2017 15:40:54 +0200
Subject: [PATCH] Fix issue 17686: [REG2.075.0] Covariant return types doesn't
 work with override in some cases

---
 src/ddmd/mtype.d           |  2 +-
 test/compilable/fix17686.d | 45 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 test/compilable/fix17686.d

diff --git a/src/ddmd/mtype.d b/src/ddmd/mtype.d
index 9f4186c67b2c..013b0c5e3a5f 100644
--- a/src/ddmd/mtype.d
+++ b/src/ddmd/mtype.d
@@ -775,7 +775,7 @@ extern (C++) abstract class Type : RootObject
 
                 // If t1n is forward referenced:
                 ClassDeclaration cd = (cast(TypeClass)t1n).sym;
-                if (cd.semanticRun < PASSsemanticdone)
+                if (cd.semanticRun < PASSsemanticdone && cd.baseok < BASEOKdone)
                     cd.semantic(null);
                 if (!cd.isBaseInfoComplete())
                 {
diff --git a/test/compilable/fix17686.d b/test/compilable/fix17686.d
new file mode 100644
index 000000000000..db82252ff4a4
--- /dev/null
+++ b/test/compilable/fix17686.d
@@ -0,0 +1,45 @@
+/* REQUIRED_ARGS:
+ * PERMUTE_ARGS:
+ */
+
+// https://issues.dlang.org/show_bug.cgi?id=17686
+
+interface INode
+{
+    @property INode parentNode();
+    @property IDocument ownerDocument();
+}
+interface IDocument: INode {}
+interface IEntityReference: INode {}
+
+class DOMImplementation(T)
+{
+    abstract class Node: INode
+    {
+        override
+        {
+            @property Node parentNode() { return null; }
+            @property Document ownerDocument() { return null; }
+        }
+
+        @property bool readonly() { return true; }
+    }
+    abstract class NodeWithChildren: Node {}
+
+    class Document: NodeWithChildren, IDocument {}
+
+    class EntityReference: NodeWithChildren, IEntityReference
+    {
+        override
+        {
+            @property bool readonly() { return true; }
+        }
+    }
+
+}
+
+void main()
+{
+	alias aaa = DOMImplementation!string;
+}
+